public BitString(byte[] data, int length = -1)
{
data = data ?? throw new ArgumentNullException(nameof(data));
var count = data.Length;
var bitCount = count << Shift;
_length = length < 0
? bitCount
: length;
if (_length > bitCount)
{
throw new ArgumentOutOfRangeException(nameof(length));
}
// If the full range of bits is to be considered, whole process is a lot simpler.
if (_length != bitCount)
{
// How many blocks will we need?
count = (int)Math.Ceiling((double)_length / BlockBitSize);
Array.Resize(ref data, count);
// If the last block is not full, zero the trailing bits which do not belong to the bitString.
var remaining = _length % BlockBitSize;
if (remaining > 0)
{
data[count - 1] &= BinaryFunctions.LowerMask(remaining);
}
}
_data = data;
}
public static BitString Random(Random random, int length)
{
var count = (int)Math.Ceiling((double)length / BlockBitSize);
var data = new byte[count];
random.NextBytes(data);
var left = length % BlockBitSize;
if (left != 0)
{
data[count - 1] &= BinaryFunctions.LowerMask(left);
}
return(new BitString(data, length));
}
public BitString Truncate(int length)
{
length = Math.Min(_length, Math.Max(0, length));
var count = (int)Math.Ceiling((double)length / BlockBitSize);
var data = new byte[count];
Array.Copy(_data, 0, data, 0, count);
var left = length % BlockBitSize;
if (left != 0)
{
data[count - 1] &= BinaryFunctions.LowerMask(left);
}
return(new BitString(data, length));
}